DNS is the “phone book” of the internet: it maps a domain name to a server's IP address. Let's break down the main record types.
A and AAAA
An A record points a domain to the server's IPv4 address, AAAA — to IPv6. This is the basic record without which the site won't open.
CNAME
An alias: points one domain to another. Often used for subdomains like www.
MX
Mail routing: tells which server receives email for your domain.
TXT
Text records for verification and email protection (SPF, DKIM, DMARC).
After changing DNS, allow up to 24 hours for caches to update worldwide, though 1–2 hours is usually enough.